1. Field of the Invention
This invention relates to an analogue electronic watch having two motors, one for driving the time display, the other for driving means for numerically displaying the day of the month, and is more particularly concerned with a watch comprising, in addition, a perpetual-calendar circuit. This circuit includes day, month and year counters and issues a date indicating signal to a control circuit which activates the second motor by causing it to move forward by a number of steps whereby the numerical display of the day of the month may correspond to the contents of the day counter, and thus agree with the date shown by a perpetual calendar.
2. Prior Art
Such watches are known and a form of embodiment thereof is described in U.S. Pat. No. 4,300,222. The watch described in this specification comprises a perpetual calendar displaying the day of the month and, possibly, the day of the week. Although the calendar is reliable when the watch operates normally, a change of cell causes the counters to be in states that are in no way related to the date since the calendar circuit is no longer able to generate correct signals.
After a change of cell, the counters, the day of the month display and the time display of the watch, need to be corrected. Correcting the day of the month display is done in the usual way. However, correcting the counters is hardly possible for the user or for a watch-repairer not having the required equipment. Indeed, to diminish the time spent, each counter must be corrected separately and this involves complex manipulations. Moreover, for such correction to be possible, the contents of the counters must be known and this information is not displayed by the watch.
A change of cell can therefore only be performed in the factory or in an after-sales service centre and this places an undesirable constraint in the use of an otherwise most practical watch.